From the starting position, step your left foot forward and drop your right knee down into a lunge. Lower the right knee down until the left quadriceps (thigh) is parallel to the floor. Keep the weight of your left leg primarily on the heel and do not allow the left knee to come out in front of your toes, or you'll risk knee and other injury (see Photo 2).

From the bottom of the lunge, stand up, step forward with your right leg, and drop your left knee down into a lunge on the other side (see Photos 3 and 4).

Do a total of 12 pairs of walking lunges for your first set. For your second set, repeat the steps above, but try holding the dumbbells up at your shoulders while you do the lunges.

About Billy Polson: Billy Polson is the founder and co-owner of DIAKADI Body training gym, which was voted the best personal training gym in San Francisco by CitySearch in 2006. A competitive swimmer and triathlete in his own right, Polson has over 15 years of experience working as a coach and trainer, and was recently named by Men's Journal Magazine (December 2005) as one of the Top 100 Trainers in America.